Revenues - Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2019	May 31, 2018	May 31, 2019	May 31, 2018
Disaggregation of Revenue [Line Items]
Revenues	$ 8,497,941	$ 9,087,328	$ 23,465,769	$ 24,099,365
Energy
Disaggregation of Revenue [Line Items]
Revenues	1,738,045		5,374,110
Ag
Disaggregation of Revenue [Line Items]
Revenues	6,745,115		18,045,057
Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	14,781		46,602
ASC 606
Disaggregation of Revenue [Line Items]
Revenues	3,783,752		9,415,783
ASC 606 | Energy
Disaggregation of Revenue [Line Items]
Revenues	1,544,533		4,826,762
ASC 606 | Ag
Disaggregation of Revenue [Line Items]
Revenues	2,234,378		4,574,203
ASC 606 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	4,841		14,818
ASC 815
Disaggregation of Revenue [Line Items]
Revenues	4,678,601		13,922,624
ASC 815 | Energy
Disaggregation of Revenue [Line Items]
Revenues	193,512		547,348
ASC 815 | Ag
Disaggregation of Revenue [Line Items]
Revenues	4,485,089		13,375,276
ASC 815 | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	0		0
Other Guidance
Disaggregation of Revenue [Line Items]
Revenues	35,588		127,362
Other Guidance | Energy
Disaggregation of Revenue [Line Items]
Revenues	0		0
Other Guidance | Ag
Disaggregation of Revenue [Line Items]
Revenues	25,648		95,578
Other Guidance | Corporate and Other
Disaggregation of Revenue [Line Items]
Revenues	$ 9,940		$ 31,784